Hammer head having reboundpreventing means



J. w. KAHLEN' 2,604,914

HAMMER HEAD HAVING REBOUND-PREVENTING MEANS July 29, 1952 Filed Jan. 9, 1959 mvzu'rpn JOHANNES MLLMM KAHLEN Ar'ronusvs Patented July 29, 1952 OFFICE HAMMER HEAD HAVING REBOUND- I l PREVENTING MEANS Johannes William Kahlen, West Vancouver,

- "British Columbia, Canada Application January 9, 1950, Serial No. 137,610 In Canada. May 13, 1944 1, This invention relates to improvements in striking articles, and particularly in hammers.

- This application .is a continuation in part of the applicantsapplication Serial Number 592,336, filed May 7, 1945, now abandoned, as to subject matter common thereto. f 1 '1 7 When a hammerfis, moved to strike an object, part of the kinetic energy developed is utilized in doing work on the object, part is dissipated in the form of heat, and part is converted into potential energy in the form of distortion in the striking surface of-the hammer. .The distortion of. the striking surface has potential'energy much the same as a compressed spring, and this causes the hammer to recoil. If a force is appl to t hammer-at the time that the. recoil would norslidably mounted therein is notvery successful, 7

because theslug delivers on the end of the chamber one or more impact blowsof extremely short duration. The slug tends to stop'the recoil of the hammer head, but the slug itself then recoils and must have its own kinetic energy absorbed by friction on the walls of the chamber." 'Thus,

the slug creates undesirable vibration oroscillation in the hammer. 1

Powdered material has been used in the same manner as a solid slug. It hasbeen foun'd that this material tends to pack anditf then becomes I the equivalent oi a solid'body' and actsin practically the samemanner as-the slug;'or hammer. l I

A charge of round shot in a chamber behind the striking face of a hammer is not veryhelpful since "there is relatively little jfriction owing to their shape; someor the shot strikes directly on top of othershot and tends to 'oscillate;" other shot strikes between preceding shot and directs kinetic energy at an angle to the direction of movement of the hammer, tending to reduce striking power; and the required size of chamber and hammer must be out of proportion for a particular weight of hammer. v

It has been found that a -no-b'ounce*"-hammer 7 4 Claims; (Cl. 14536) may be produced by utilizin a charge of irregularly shaped, hard, heavy particles in a chamber immediately behind its striking head. It is desirable to have the particles shaped as irregularly as possible, although reasonably good results may be obtained by almost any shape other than round, and it is to be understood that the term irregular is intended to cover all these shapes. These irregularly shaped particles prevent recoil, eliminate vibration or, oscillation, produce a prolonged blow on the object being struck instead of a quick sharp blow, andthey permit a lighter hammer to be used fora certain job than would otherwise be possible. 5

In operation, the irregularly shaped particles deliver on the end of the hammer-"chamber a blow which is not asingleimpact, but a rapid succession of overlapping impacts whose resultant is an impulse of much longer duration than the single impact of a'solid slug or of the equivalent thereof. By having the chamber filled with a proper amount of these particles, the prolonged impulse begins while the hammer head is still in contact with the object being struck, so that the hammer delivers an initial sharp blow immediately followed by an impulse of appreciable duration. Each of the overlapping impacts tends to deaden any recoilof the preceding impact. The friction and'interfitting of the irregularly shapedpar'ticlesprevents them from separating as they travel towards the chamber end sufiiciently to disperse theirstriking power to a point where it isnseless and yet'after impact they cannot rebound as a mit because of the individual particles and theydeaden any rebound.

Another important ,factor in this invention is the size or coarseness of-fthe irregular, particles and the amount of unfilled space "to be left in the hammer chamber. ,In order; to-{determine this, the size ofthehammen thei-weight of its empty headand the'recoil quality of its striking surface must be takeninto consideration; ,Furthermore; it is always; desirable to make a hammer as compact aspossibl-to do the work for which it isintended. -"When"the recoil is about to begin afteftheblo'w hasib'een's'truck, the load of loose particles in the hammer chamber must be loose enough to' eig-pend its total energy in the direction "of the blow substantially in successive impacts andthey must beclose enough to the end of the 'chambei -tb come -into Contact th'erewith instantly afterthe' blo'w has struck in order to prevent-, "the jcreation bf -a secbh'dblow.

1 Furthermor there should notfbe enough movement to be felt' b the p ersbn'iu's'ing the hammer.

ticles must be materially increased in relation to the weight of the empty hammer head.

The coarseness of the particles depends upon the weight of the material forming them. It is desirable to keep these particles as coarse as possible while keeping the hammer as small as possible. However, the particles must not be so coarse that they tend to act as individual slugs. Care must be taken thatthe particles are not so small that they act as a powder and therefore pack and tend to producethe same results as a solid hammer or a solid slug in a hammer.

The specific gravity of the irregularly shaped particles must be as high as possible, and they must be very hard in order that they will not pulverize as a result of a great deal of use of the hammer. For example, steel, brass or hard lead alloys maybe used.

Good results have been obtained by using a mixture of comparatively large and small irregularly shaped particles. The object of this is to get as much weight into a given space as pos sible. The small particles tend to fill the spaces between the larger particles, while the latter prevent the former from packing.

An example of this invention is illustrated in the accompanying-drawings, in which.

Figure l is a side elevation of a hammer,

Figure 2 is a side elevation of a hammer with one of its striking heads removed,

Figure 3 is a side elevation, partly in section, of a hammer, and

Figure 4 is an enlarged and exaggerated sectional view showing the particles in the hammer.

The drawings illustrate a hammer of the type having two striking heads, but it is to be understood that it may have only one such head and it may be any desired shape.

The illustrated hammer consists of a body it which is usually formed of a suitable metal, although it may be any other material which will stand up underuse. A striking head i I is positioned at each end of the body [0. Each head may be formed integrally with the body or, as

shown, it may be made separate and secured to the body in any convenient manner. For example, the head may be formed of steel in order to stand up to heavy -work,-or it maybe formed of suitable plastic material which may; be used to hammer materials without marking them.

In this example the body it! is provided with a pin 15 projecting outwardly from each end thereof, and each head ll, whichis formed of a suitable plastic material, hasahole l6 drilled- A chamber I9 is formed in the hammer body immediately behind the striking heads II. For the sake of; convenience in manufacture, the

, hammer body may be in the form of a tube having a plug20 closing each end thereof. 1 One of the plugs has a tapped hole..22 extending therethrough in which a screw 23 is threaded. This screw has no head so that it can be turned into the hole until its outer end is flush with the outer end of the plug 20.

A charge of irregularly shaped particles 26 almost fills the chamber 19, see Figure 3. There should be only enough empty space in the chamber to allow the particles to expand slightly immediately before and after a blow is struck with the hammer. The total weight of the particles in the chamber and the amount of unfilled space therein depends upon the recoil quality of the striking head of the hammer, the size of the hammer and the weight of the empty body. The greater the recoil quality of a striking head, the heavier should the particles be and the greater the unfilled space in the chamber. However, it is to be understood that the amount of clearance is very small in any case.

A handle 30 is connected to the body I!) in any convenient manner. For example, a ferrule 3| is connected to the hammer body substantially midway between its opposite ends and projects outwardly therefrom at right angles to the length thereof. A wedge 32 is inserted part way into a slot in the end of the handle, see Figure 2, and when this end is inserted in the ferrule, the handle is hammered into the ferrule until the wedge, striking the hammer body, firmly retains the handle in position.

When a blow is struck with the hammer, the particles 26 move towards the end of the chamber 19 immediately behind the head H which con tacts the object being struck. This loosens the particles up so that they deliver a rapid succession of overlapping impacts on the chamber end whose resultant is an impulse of comparatively long duration. At this time the particles come together into a compact body and each successive impact prevents the particles ahead of it from rebounding. Thus, the particles prevent the hammer from rebounding. Immediately after this action, the particles tend to disperse or loosen up so that they themselves do not cause any vibration or oscillation in the hammer.

Figure 4 diagrammatically illustrates the irregularly shaped particles in the chamber. It will be seen that they overlap and interfit with each other so that they cannot move towards the impact end of the hammer in a stream, but must more or less move as a loose body. Furthermore, it is practically impossible for a particle striking particles ahead of it to force them in a lateral direction. It is this fact, along with the fact that the particles deliver a rapid succession of overlapping impacts, which enables this hammer to deliver a much harder blow than is possible with any other hammer of a similar size and weight.

The irregularly shaped particles prevent any recoil in the hammer and they eliminate any vibration This is very desirable since it prevents the stinging in the hand of the person holding the hammer which is apparent when a blow is struck against a hard object with any known type -0f hammer. A prolonged blow greatly increases the effect of the hammer and it allows the hammer to be made as compact as possible.

What I claim as my invention is:

l. A hammer comprising a body, a striking head at one end of the body, a chamber formed in the body immediately behind the head, a charge of irregularly shaped hard, heavy particles almost filling the chamber, and a handle connected to the body. r

2. A hammer comprising an elongated body, a

striking head at one end of the body, a chamber formed in the body immediately behind the head, a charge of irregularly shaped hard, heavy particles ahnost filling the chamber, and a handle connected to the body and projecting outwardly substantially at right angles to the length thereof.

3. A hammer comprising a body, a striking head at one. end of the body, a chamber formed in the body immediately behind the head. a charge 01 coarse irregularly shaped hard, heavy particles almost filling the chamber, and a handle connected to the body.

4. A hammer comprising a body, a striking head at one end of the body, a chamber formed in the 6 7 body immediately behind the head, and a charge of irregularly shaped hard, heavy particles almost filling the chamber.

J OHANNES WILLIAM KAHLEN.

REFERENCES CITED The following references are of record in th file of this patent: 

